Random Area and Perimeter












0












$begingroup$


Lt A and L denote the area and perimeter of a rectangle with length $X$ and height $Y$, such that $X$ and $Y$ are independent, and uniformly distributed on $(0,1)$. Find the density function of $A$ and $L$.



Will it just be $$f(x,y) = 2xy(x+y)$$



The above is just my guess and likely wrong, because when I use it to calculate $mathbb{E}(A)$ and $mathbb{E}(L)$ , I get the wrong values, so what will be the distribution function?










share|cite|improve this question









$endgroup$












  • $begingroup$
    area is a product of two uniform random variable. see answers of this question. perimeter is twice the sum of two uniform random variable. Its PDF is a triangular shaped function.
    $endgroup$
    – achille hui
    Dec 3 '18 at 13:58










  • $begingroup$
    You do not need to find the joint density (which is what your $f$ looks like), and this is pretty hard to do.
    $endgroup$
    – Mike Earnest
    Dec 3 '18 at 15:58










  • $begingroup$
    Ok, I think I interpreted the question wrong
    $endgroup$
    – user601297
    Dec 3 '18 at 20:05
















0












$begingroup$


Lt A and L denote the area and perimeter of a rectangle with length $X$ and height $Y$, such that $X$ and $Y$ are independent, and uniformly distributed on $(0,1)$. Find the density function of $A$ and $L$.



Will it just be $$f(x,y) = 2xy(x+y)$$



The above is just my guess and likely wrong, because when I use it to calculate $mathbb{E}(A)$ and $mathbb{E}(L)$ , I get the wrong values, so what will be the distribution function?










share|cite|improve this question









$endgroup$












  • $begingroup$
    area is a product of two uniform random variable. see answers of this question. perimeter is twice the sum of two uniform random variable. Its PDF is a triangular shaped function.
    $endgroup$
    – achille hui
    Dec 3 '18 at 13:58










  • $begingroup$
    You do not need to find the joint density (which is what your $f$ looks like), and this is pretty hard to do.
    $endgroup$
    – Mike Earnest
    Dec 3 '18 at 15:58










  • $begingroup$
    Ok, I think I interpreted the question wrong
    $endgroup$
    – user601297
    Dec 3 '18 at 20:05














0












0








0





$begingroup$


Lt A and L denote the area and perimeter of a rectangle with length $X$ and height $Y$, such that $X$ and $Y$ are independent, and uniformly distributed on $(0,1)$. Find the density function of $A$ and $L$.



Will it just be $$f(x,y) = 2xy(x+y)$$



The above is just my guess and likely wrong, because when I use it to calculate $mathbb{E}(A)$ and $mathbb{E}(L)$ , I get the wrong values, so what will be the distribution function?










share|cite|improve this question









$endgroup$




Lt A and L denote the area and perimeter of a rectangle with length $X$ and height $Y$, such that $X$ and $Y$ are independent, and uniformly distributed on $(0,1)$. Find the density function of $A$ and $L$.



Will it just be $$f(x,y) = 2xy(x+y)$$



The above is just my guess and likely wrong, because when I use it to calculate $mathbb{E}(A)$ and $mathbb{E}(L)$ , I get the wrong values, so what will be the distribution function?







probability probability-distributions random-variables uniform-distribution expected-value






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Dec 3 '18 at 13:38









user601297user601297

39219




39219












  • $begingroup$
    area is a product of two uniform random variable. see answers of this question. perimeter is twice the sum of two uniform random variable. Its PDF is a triangular shaped function.
    $endgroup$
    – achille hui
    Dec 3 '18 at 13:58










  • $begingroup$
    You do not need to find the joint density (which is what your $f$ looks like), and this is pretty hard to do.
    $endgroup$
    – Mike Earnest
    Dec 3 '18 at 15:58










  • $begingroup$
    Ok, I think I interpreted the question wrong
    $endgroup$
    – user601297
    Dec 3 '18 at 20:05


















  • $begingroup$
    area is a product of two uniform random variable. see answers of this question. perimeter is twice the sum of two uniform random variable. Its PDF is a triangular shaped function.
    $endgroup$
    – achille hui
    Dec 3 '18 at 13:58










  • $begingroup$
    You do not need to find the joint density (which is what your $f$ looks like), and this is pretty hard to do.
    $endgroup$
    – Mike Earnest
    Dec 3 '18 at 15:58










  • $begingroup$
    Ok, I think I interpreted the question wrong
    $endgroup$
    – user601297
    Dec 3 '18 at 20:05
















$begingroup$
area is a product of two uniform random variable. see answers of this question. perimeter is twice the sum of two uniform random variable. Its PDF is a triangular shaped function.
$endgroup$
– achille hui
Dec 3 '18 at 13:58




$begingroup$
area is a product of two uniform random variable. see answers of this question. perimeter is twice the sum of two uniform random variable. Its PDF is a triangular shaped function.
$endgroup$
– achille hui
Dec 3 '18 at 13:58












$begingroup$
You do not need to find the joint density (which is what your $f$ looks like), and this is pretty hard to do.
$endgroup$
– Mike Earnest
Dec 3 '18 at 15:58




$begingroup$
You do not need to find the joint density (which is what your $f$ looks like), and this is pretty hard to do.
$endgroup$
– Mike Earnest
Dec 3 '18 at 15:58












$begingroup$
Ok, I think I interpreted the question wrong
$endgroup$
– user601297
Dec 3 '18 at 20:05




$begingroup$
Ok, I think I interpreted the question wrong
$endgroup$
– user601297
Dec 3 '18 at 20:05










0






active

oldest

votes











Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3024071%2frandom-area-and-perimeter%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematics Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3024071%2frandom-area-and-perimeter%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

Bundesstraße 106

Verónica Boquete

Ida-Boy-Ed-Garten